Antidetonating device



April 27, 1943.

G. M. BICKNELL ANTI-BETONATING DEVICE Filed Feb. 5, 1942 ATTORNEY Patented Apr. 27, 1943 ANTIDETONATING DEVICE George M. Bicknell, St. Louis, Mo., assignorto Carter Carburetor Corporation, St. Louis, Mo., a corporation'of Delaware Application February 5, 1942, Serial No. 429,605

(c1. 12s-119i 8 Claims.

This invention relates to charge forming devices for internal combustion engines and more particularly to means for introducing engine exhaust gases into the fuel-air mixture.

In order to utilize. more satisfactorily, engine fuels of low octane rating in high compression engines, it is proposed herein to introduce into the mixture, formed with such fuel, variable quantities of engine exhaust gases under conditions of high volume operation. The dilution of the mixture with the inert constituents as well as the introduction of the H2O contained in the exhaust gases will reduce detonation.

It is, therefore, an object of the present invention to provide means for introducing exhaust gases into the fuel-air mixture under operating conditions In which the volume taken in by the engine cylinders is at or near maximum.

It is a further object of the present invention to provide means for introducing exhaust gases into the carburetor mixture conduit in a zone of comparatively high veloci-ty and suction.

It is a further object of the present invention to control the introduction of exhaust gases into the mixture in accordance with the tempera ture.

Other objects and advantages will become apparent upon perusal of the following description and accompanying drawing in which:

'I'he iigure is a schematic arrangement embodying a form of the present invention and in which are shown portions of an engine intake and Vexhaust manifold, a carburetor, and the device for introducing exhaust gases into the mixture.

Numeral I generally indicates a downdraft carburetor having a constant level iuel chamber 2 for receiving fuel, a nozzle 21 communicating therewith and discharging into the carburetor mixture conduit 3, a choke valve 2B and a mixture control or throttling valve 5. The carburetor I may be of any suitable type arranged to pro duce a combustible mixture of fuel and air and having at least one constriction as indicated at 4. The carburetor is mounted on the intake manifold 6 in any suitable manner as by screws (not shown). Lying below and parallel to the intake manifold is the exhaust maniioldlhavinglan outlet indicated at il.

A conduit 9 for conducting exhaust gases from the exhaust manifold to the carburetor mixture conduit at a point near the throat of the constrlction l is provided and has interposed therein a control valve IU, a strainer and flame bathe II, and a control valvelli. For actuation of the control valve I2 the pressure responsive device I3 is provided which comprises a collapsible bellows Il having a suction connection I5 to the intake manifold 6.

The bellows Il is rigidly mounted at one end on a bracket I6 which may be attached to any adjacent stationary part of the engine by screws Il. The valve I2 is provided with an operating lever IB which is connected to the free end of bellows i4 by the connecting rod IB. spring 2li disposed within the bellows Il normally urges the free end of the bellows toward the left in an extended position and, consequently, control valve I2 in an open position as indicated.

The control valve III is also provided with an operating lever 2l which is connected to a temperature responsive bi-metallic coll 22 by means of the link 23. Thev coil 22 is rigidly mounted at iis center and so wound (with the metal having.r the greatest coeiTicient of expansion on the outside) so as to uncoil with decreasing temperature. It will be seen, therefore, that with increasing'temperatures the free end 24 of the coil will move clockwise thus moving control valve III from the closed position. as shown, to an open position. Stops 25 and 26 are provided to limit the travel of the free end of the coil 22. The coil 22 is so constructed and disposed as to respond to engine temperatures incidental to normal operation to move the valve I0 to an open position. y

In operation. after the engine has been warmed up to normal operating temperature, the valve I0 will be in an open position. Valve I2 Will be positioned 'in accordance with the pressure existing in the intake manifold. The position of the throttle valve 5 and the load on the engine will. obviously. be the factors determining the pressure in the Intake manifold. It is the intention to calibrate the suction opposing spring 20 so as to cause valve I2 to be opened at such manifold pressures which correspond to those volumes of ow which would. without the introduction of exhaust gases, cause objectionable detonation. It will be understood that this calibration will, of course, vary for different engines and different octane fuels,

At higher intake manifold suctlons. corresponding to throttled or high velocity nonthrottled operation wherein the volume of the intake charge is less than that which would cause detonation, the valve I2 will be closed and the engine will operate on the conventional fuel-a mixture.

10aa reason for controlling the flow oi exhaust gases to the mixture conduit in accordance with the temperature is that: during cold starting when it is desirable to create a high suction on the fuel nozzle 21 by closing the choke valve 28 to obtain the rich mixture required i'or starting. it is necessary to close the conduit 9 lest this high suction be unduly relieved. Another reason being that. during the warming-up period, combustion temperatures and pressures will be less than those attained after the engine has reached a normal operating temperature and, therefore, the tendency to detonate will be less. thus requiring less or no introduction of exhaust gases. By providing a constriction at or posterior to the discharge point of the fuel nozzle and introducing the exhaust gases at this constricted point, a better mixture of the exhaust gases and the fuel-air mixture is attained. Also, the reduced static pressure attending the comparatively high velocities at this restricted point assists in increasing the flow of exhaust gases through conduit 9.

The foregoing description and accompanying drawing are intended to be illustrative and not limiting and the exclusive use of all modifications within the scope of the appended claims is contemplated.

I claim:

l. The method of controlling combustion pressure in the combustion chamber of an internal combustion engine operating on a combustible mixture of liquid fuel and air which comprises dlluting the mixture with exhaust gases of the engine, and varying the degree of such dilution in accordance with both the temperature of the engine and the suction in the intake manifold.

2. In an internal combustion engine. a carburetor having a mixture conduit, intake and exhaust manifolds, a conduit connecting the manifolds whereby exhaust gases may be caused to enter said intake manifold by the suction conditions therein, a normally closed valve l controlling said conduit, said valve being moved toward open position upon increase in engine temperature conditions, additional means closing said conduit, and suction operated means for moving said last-named means to open said conduit. said suction operated means being responsive to manifold pressure conditions dened by periods of normal detonation in said engine.

3. In an internal combustion engine, a carburetor having a mixture conduit, intake and exhaust manifolds, a conduit connecting the manifolds whereby exhaust gases may be caused to enter said intake manifold by the suction conditions therein, means normally closing said conduit when the engine temperatures are low, and means opening said conduit when the manifold pressures are such as to normally cause engine detonation.

4. In an internal combustion engine. a carburetor having a mixture conduit. intake and exhaust manifolds, a conduit connecting the manifolds whereby exhaust gases may be caused to enter said intake manifold by the suction conditlons therein, means closing said conduit when the engine temperatures are low, and means opening said conduit as the engine temperature approaches normal and the manifold pressures are such as to normally cause engine detonation.

5. In an internal combustion engine, a carburetor having a mixture conduit, intake and exhaust manifolds, a conduit connecting the manifolds whereby exhaust gases may be caused to enter said intake manifold by the suction conditions therein, means normally closing said conduit when the engine temperatures are low. independent means controlling said 'conduit, said last-named means being normally closed regardless of temperature, and being opened by manifold pressures tending to cause engine detonation.

6. In an internal combustion engine. a carburetor having a mixture conduit, intake and exhaust manifolds, a conduit connecting the manifolds whereby exhaust gases may be caused to enter said intake manifold by the suction conditions therein, means normally closing said conduit when the engine temperatures are low and gradually moved to open said conduit as the engine temperatures increases, and independent means normally closing said conduit, said lastnamed means being moved toward open position by manifold pressures regardless of engine temperature.

'l'. In an internal combustion engine, a carburetor having a mixture conduit, intake and exhaust manifolds, a conduit connecting the manifolds whereby :xhaust gases may be caused to enter said intake manifold by the suction conditions therein, means normally closing said conduit when the engine temperature is low and gradually opening said conduit as the engine temperature increases, and means independent of the temperature controlled normally closing said conduit. said last-named means being operable to open said conduit when the manifold pressures are within a predetermined range.

8. A method for reducing the detonation in an internal combustion engine which includes recycling a portion of the exhaust gases from the exhaust manifold to the mixture in the intake manifold only at predetermined periods of the engine operation as dened by normal operating temperatures and manifold pressures tending to cause detonation.

GEORGE M. BICKNEIL. 

